Fluid-metering valve for hydraulic motor control systems



March 1953 c. B. LIVERS ET AL 2,632,470

FLUID-METERING VALVE FOR HYDRAULIC MOTOR CONTROL SYSTEMS Filed Sept. 25, 1950 37 J4 av /zap. ,2 36 /310" {z n p 2 37 i4 V 45, U I f "22 T9- 2 27 Z6 2; 24 2; 28 ;z 3/ 17 M IN VEN TORS c. B. LIVERS A. A. MEDDQCK ATTORNEY Patented Mar. 24, 1953 FLUID-METERING VALVE FOR HYDRAULIC MOTOR CONTROL SYSTEMS Carlos B. Livers, North Hollywood, and Alvin A. Meddock, Van Nuys, Calif., assignors to Bendix Aviation Corporation, South Bend, Ind., a corporation of Delaware Application September 25, 1950, Serial No. 186,664

8 Claims.

This invention relates to shut-off valves for hydraulic motors for automatically stopping such motors when they have been actuated through apredetermineddistance, and particularly to valves for such purposes that respond directly to the quantity of fluid flowing through the motor as distinct from those that are mechanically actuated by the motor.

An object of the invention is to provide a practicable automatic valve that can be inserted at any point in one of the lines between a hydraulic motor and the usual manual control valve therefor, and that will limit the range of ;movement or stroke of themotor in one direction to a definite predetermined distance without limiting its operation in the other direction.

Another object is to provide an automatic valve of the type referred to that blocks the line after a predetermined amount of fluid has passed through it in one direction, but is quickly reset by momentary reversal of fluid flow, to again permit the predetermined amount of fluid to flow in the one direction, so that a motor in series with the valve can be moved either a predetermined distance or a multiple of that distance.

Another object is to provide a valve for blocking a line after a predetermined quantity of fluid has flowed therethrough, which valve is relatively accurate and. yet simple and inexpensive.

Other more specific objects and features of the invention will appear from the description .to follow.

Briefly, the automatic valve in accordance with [the invention comprises a reciprocable valve movable between two limits by a small piston ,and blocking fluid flow in one limit position.

The piston is moved through its stroke at a speed proportional to the rate of fluid flow through theline in which the valve is inserted, but slower inthe closing direction of the valve than in the a fraction of the total flow is obtained in accordance with theinvention by means of a small motor connected in the line and mechanically coupled to a smaller pump that meters the fluid displaced by the piston.

l 'A- full understanding of the invention may be had from-the following detailed description with -retcrenceto thedrawing. iii-which: 4.

Fig. 1 is a schematic diagram showing one embodiment of the inventionyand Fig. 2 is a schematic diagram showing a modification of the valve shown in Fig. 1.

Referring first to Fig. 1, a valve II] in accordance with the invention is shown connected in one of the lines ll extending between one end of a hydraulic motor cylinder l2 and the usual 4-way control or selector valve I3, -which is manually operated to cause the piston 12a of the motor cylinder I2 to move in eitherdirection. The other end of the motor cylinder I2 is connected by'a line [4 to the 4-way valve l3, and the latter is connected by a supply line I5to a pump I 6 and'by an exhaust line IT to a reservoir H8. As is well known, the 4-way valve [3 may be moved between a position in which both the lines II and I4 are blocked, to maintain the motor piston l2a stationary, into a position in which the pressure line I5 is connected to the line II, and the exhaust line I! is connected to the line M, for moving the piston [2a to the right, or into another position in which the pump line [5 is connected to the line I l, and the exhaust line I! is connected to the line II for moving the motor piston [2a to the left. 4

There are many applications in which it is desirable to automatically limit the stroke of the motor piston l2a. The valve [0 is provided for this purpose, and it functions to block the line II during leftward movement of the piston I2a to stop the latter after a predetermined quantity of fluid has flowed from the left end of the motor cylinder I2 through the line II andtheivalve' lfl.

The valve I0 has only twoexternal ports, namely a first port I8 connected to that section of the line I I leading to the control valve l3, and a second port I9 connected to that section of the line I l leading to the left end of the motor cylinder I2. The first port I8 is connected by a passage 20 to one side of a gear motor 2|, the other side of which is connected by a passage 22 to a cylinder 23 near the right end thereof. The right end of this cylinder constitutes a valve seat 24 cooperatingwith a poppet valve 25 that is connected by a rod 26 to a piston 21 movable in the cylinder 23. The cylinder 23 is communicated at its right nd. by the valve seat, with ,spring 32 may be provided between the seal 3| and the poppet 25 to urge the poppet and the piston 21 to the left, but this is not essential.

The left end of the cylinder 23 is communicated by a passage 33 with one side of a gear pump 34; the other side of whichis connected by a passage=..35ito1the" first port. it; The gear pump 34 is shown as comprising two gears 34a and 34b respectively, and the gear 34a is coupled. by a shaft 36 to one of the gears Zia of the ear motor 2|.

The gear pump 34 is bypassed bya passage'fiil' containing a check valve 3.8;for:permitting--flovr past the gear pump 34 fromKthefirstIport lfitwhile: preventing reverse flow. Likewise, the=gear motor 2| is bypassed by a passage 39 containing a check valve 4!} which permits flow past the: gear motor from the first port is while preventing reverse flow. For a purpose that will be explainedincom nection with the operation of the device, the

olieck -valve. tii 'isurgedintucclosed positiom by a spring of appreciable strength so that::ii-.;fimctions as: alight relief:valveatoprevent fiow' from the first portifi pastithezgearimotor 255 until; the

" pressure inthe port! 8: has risen toranappr'eciable value. On the' otheri hand;. th'ei valve- '3Bris provi'ded only: as a check valve to" prevent reverse now and itsspring-is suzli'ghtas to be" overcome by a very light" pressure substantially less: than i that required to: openthe valveztit;

"The-system ofiFig; lifunctionsraafollows: The valve isshown/1n position in: which thesmotor piston 'iil'a: been' stopped during leftward movementby -clo'sure of' th'e poppet 2:5 against theseat 24g whichblockstheline iii When itis" desired -to move" theimotor piston "Ila/to the right, the i -may control? valve iisiis manipulated te-connect thepump output K111281115 with the'line H, and connect the exhaust line H with the li'n'e l4. Pressureufluid thereupon -enters-thefirst port 1 8 l oflthe-valve lill'and flows through the-passages 35 and 37' past the check valve -3B and into the-lett end of the cylinder 23, moving the piston 2T to the right in so: doing 'and" opening thepoppet 25 until the lattertabuts against the stoprod 2 91 During-this initial phase ofthebperation; fluid does not =fiow through3the gear-pumpt i -or' through the gear" motor .215, because the resistance to 'movement' of thoseelements is greater than the resistance afforded by the-check valve 38 and the piston 21. Likewise,

it; does notfiow through the passage 39 because the-resistance of thecheckvalve iil is sufiici'ent "to. preventtsuch flow; However, after movement ofthepiston 2'! has been terminated 'byl contacting the stop= 239, the flowof fluid throug-h thepa'ssage 3'1 and the passage is blocked', and the pressure then risesto a value-sufficien'ti to open the check valve -30 and permit the fluid toaflow through the passage 39' and through the: open valve seat 2 4 into the chamber 28, and through the second port F9 to the left end of the motor cylinder l2, moving the piston IZa therein to the 'hausting the fluid through the line Ii into the second port it of'the valve Hi This fluid flows through the chamber 28 and through the open valve seat 2 3, and into the passage 22. The fluid is blocked from flowing through the passage 39 by the check valve 36 so that it must flow through the gear motor 2!, rotating the latter in so doing. The fluid: afterpassingithrou'gh: the gear motor flows through the pas'sage-QOtoth'efir-St port i8, and thence back to the control valve I3. The gear motor 2i rotates at speed proportional to the flow of fluid therethrcugh, and therefore proportional tolthe movement of the motor piston !2a, and it drives'the gear motor 34 at a speed proportional to? the movement ofthe motor piston. The gear 'niotor'34 therefore pumps fluid from the left end of-the-cylinder-23 through the passage 33 back tothefirstport is at a rate proportional to the movement; of. the motor piston l2a. During this time, the pressure of the fluid enterin the second -port' I9 is applied through the cylinder 23 to the right end of the: piston 27 urging the latter to thelleft, and it moves leftward'asrfiastasf the fluid-tin the leftaen'd of the cylinderis exhausted therefrom by' the; gear pumrrfi iz when the motor piston iZm has traveled a predetermined distance to the left,;the=1 poppet 2% closes: against the scat 24-,positivelyblo'cking any turther fiow of fluid through the line-H andstopping: the motor piston Him in? a: position determined: by the .amountof fluid thatisrequired to move the poppet 25 from itsv rightmostiposition against the stop z'sintoits'leftmcst positionzagaihst the seat 2141 Thi'scompletes a l-cycle of: operation.

A. check valve-53 1s shown b'etween the passage 2i! and the gear motor 2"! to positivelyiprevent flow of the fluid from the first port !8 through the-motor '2 l However, ordinarilyithezresistance to motion of the gear motor is' sufficiently'great to prevent such flowpand 'the check valve QB 'c'a-n be dispensed with.

The gear motor?! is preferably of 'much larger capacity than the gear pump 3%. H'e'nc'e the amount of" fluid displaced by the piston 2'! can be a very small fraction of the total volume of fluid flowing through the gear I'n'otor' 2l. This makes it possible for the cylinder 23 andthe piston 2'! to be relatively small and compact. Furthermore, since when pressure fluid is -supplied to the first port iii to'move the piston iflwto the right, all of-the fluid-'initiall-y-flows'past th'e check valve 38' into the-left end of thecylinder'23, this cylinder is filled very rapidly, and the piston 2! is moved through its full stroke-into'eontact with the stop 29 beforethe. .motorpiston 211 has traveled any appreciabledistance, Thi'sinsures positive resettin of"the val've'25 againstthe'stop 29 on each operation. Furthermore, it permits the operator, if he so desires, to move the motor piston I 2a afurther'distanceto the-l'eft by admitting pressure fluid into the line H just long enough to restore the piston 2? intoits rightmost position (which operation moves themetor' piston 12w hardly at'all) and then immediately reversing'the valve I3-to' again'supply pressureflu-id to the line Hi. The motor piston I'Za then moves a further distance to the left equal to its normal movement from the right end of its stroke; because the movement of the pistonZ-i will again meter the normal amount of fluid.

Obviously the position in which thepiston (2a is normally stopped'may be variedbetween wide limits by adjusting the stop 29.

As has been previously indicated, the spring 32 urging the piston 21 to'the left is not always necessary. Ordinarily, the resistance to rotation of the-gear motor 2F will developsufficient back pressure in the cylinder- 23 to insure-movement of the piston .21 to the left as fast as fluid is pumped from the left end of the cylinder by the gear pump 34. However, by providing additional force on the piston 21 by means of the spring 32, its oper'ationcan be made more positive, particularly if the frictional resistance to movement of the piston 21 in the cylinder 23 is unusually. large; be borne in mind that the cross-sectional area of the piston 2l. is usually very small and the force thereon resulting from pressure of fluid in the cylinder 23 may be small compared to the frictional resistance to movement.

Insteadof relying upon the spring 32 and upon the pressure'of fluid in the cylinder 23 to move the piston 2'! to the left, the fluid exhausted from the left end of cylinder 23 by the gear pump 34 can be usedto positively force the piston 21 to the left. An arrangement whereby this is accomplished is shown in Fig. 2.

In Fig. 2, the general arrangement is the same as in Fig. 1 and the corresponding parts bear the same reference numerals. However, whereas in Fig. 1 the passage 35 from the upper side of the gear pump 34 communicates with the first port 18, in Fig. 2 the corresponding passage 35! communicates with an auxiliary cylinder 50 that is formed as an extension of the chamber 28, and an auxiliary piston 5| in the cylinder 50 is connected to the valve by a piston rod 52. Hence; in Fig. 2, the fluid pumped from the left end of the cylinder.23 by the gear pump 34 is delivered to the cylinder 50 where it acts against the piston 5| to positively move the assembly consisting of the piston 21, the valve 25 and the piston 5! to the left. During operation of the motor l2 in the opposite direction (rightward), the gear pump does not rotate, and hence a check valve 54 is provided in a passage 55 connecting the right end of the cylinder 50 with the chamber 28, so

that during rightward movement of the piston 5| Most stroke-limiting valves rely upon mechanical 0 connection to the piston lZa of the motonand for thatreason either must be placed in close proximity to the motor or connected thereto by some form of lengthy mechanical linkage.

Althoughfor the purpose of explaining the in vention a particular embodiment thereof has been shown and described, obvious modifications will occur to a person skilled in the art, and we do notdesire to be limited to the exact details shown and described. 3

We claim: 1. A valve of the type described comprising a body having: first and second line ports; a cylin-' der containing a piston reciprocable therein; first passage mean-s including a pump connected to one end of said cylinder; a fluid motor mechanically coupled to said pump for driving it, and second passage means connecting said motor between said first port and the other end of said .cylinder; valve means connecting said other end to movement of said piston into said one end of said cylinder and opening said valve in all other positions; said motor being so sensed with re- In this connection, it should spect to said pump that fluid flow from said second port through said valve means "and said motor to said first port actuates said pump in direction to deliver fluid from said one end of said cylinder. I

2. A valve according to claim 1 in which said motor has substantially larger volumetric capacity than said: pump, and the volumetric capacity of said cylinder is small relative to the total volume of fluid flow through said motor required to actuate said piston through its stroke.

3. A valve according to claim 1 in which said pump is a gear pump and said motor is a gear motor.

4. A valve according to claim 1 including third passage means connecting said first port with said one end of said cylinder, and a fourth passage means connecting said first port with said other end of said cylinder, and a check valve in each of said third and fourth passage means for preventing flow therethrough from said cylinder to said first port while permitting flow in the opposite direction, the check valve in said third passage opening in response to a lower pressure in said first port than the check valve in said fourth passage, whereby fluid entering said first port first flows through said third passage into said one end of said cylinder, to move said piston away from the said one end to the limit of travel, and thereafter fiows through said fourth passage.

5. A valve according to claim 1, including adjustable stop means for variably limiting the stroke of said piston away from said one end of said cylinder.

6. A valve of the type described comprising a body having: first and second line ports; a cylinder containing a piston reciprocable therein; first passage means including a pump connected between one end of said cylinder and said first port for controlling fluid flow from said cylinder; a fluid motor mechanically coupled to said pump for driving it, and second passage means connecting said motor between said first port and the other end of said cylinder; valve means connecting said other end of said cylinder to said second port; means mechanically coupling said piston to said valve means for closing said valve means in response to movement of said piston into said one end of said cylinder, and opening said valve in all other positions, said motor being so sensed with respect to said pump that fluid flow from said second port through said valve means and said motor to said first port actuates said pump in direction to deliver fluid from said one end of said cylinder to said first port.

'7. A valve of the type described comprising a body having: first and second line ports; cylinder means containing piston means reciprocable therein; said piston means having two opposed pressure faces facing opposite ends of said cylinder means respectively; first passage means including a pump interconnecting opposite ends of said cylinder means for controlling fluid flow from one end of said cylinder; a fluid motor mechanically connected to said pump for driving it, and secondpassage means connecting said motor between said first port and said second port; valve means in said second passage means between said motor and said second port; means mechanically coupling said piston means to said valve means for closing said valve means in response to movement of said piston means into said one end of said cylinder means, and opening said valve in all other positions; said motor being so'sensed with respect to said pump that fluid new *Irom said sec ndport' th ou h: said valv means. and said motor to said first port actuates third-passage connecting. said first port to said one end of said cylinder, and containing acheck valve:- directed to preventflowfrom said cylinder t sa d fi st p rt; and a f urth vpassage co n cting the other end of said cylinder to said second port. having a check valve directed to prevent flow from said second port to said cylinder.

. CARLOS B. LIVERS ALVIN A. MEDDOCK.

No references cited. 

